1. Field of the Invention
The invention relates to clamping devices wherein the work piece is held between two adjustable anvils. Specifically, the invention comprises a “C clamp” having two adjustable anvils that maintain a fixed, non-rotating relationship as the work piece is clamped between them.
2. Description of the Related Art
C clamps are commonly used hand tools used to hold or immobilize a work piece between two adjustable anvil surfaces. Please refer to FIG. 1 (prior art). In C clamps of the prior art, one anvil 104 is rigidly attached to the C shaped frame 102, and the movable anvil 106 is mounted on a screw device 110 which rotates via handle 112 to direct the movable anvil 106 surface toward the fixed anvil 104. The movable anvil 106 is typically mounted on a ball joint 108 which allows the anvil 106 to stop rotating after contact with the work piece is engaged, theoretically allowing compression of the work piece without transferring a rotational torque. However, in actual usage, the friction generated by the increased clamping pressure causes the ball joint to freeze up, imparting torque to the work piece. This often causes the clamp to “walk” off the work piece and limits the amount of compression force that can be applied.
What is needed is an improved clamping device wherein both anvil surfaces remain fixed, maintaining a non rotating relationship as the work piece is clamped between them.